Self venting drain valve

Abstract

A self venting drain valve (10) for a fuel filter/water separator unit or other air tight fluid container is disclosed. The valve includes a arcuately elongated fluid hole (18) and a vent hole (20) in a lower wall (12) of the unit. A cylindrical movable member (36) is mounted for rotational movement on a pivot post (16) which extends downward from the unit. The movable member includes an upper planar face (40). A arcuately elongated slot (42) in the movable member is in fluid connection with a liquid outlet (46). The movable member also includes an air passage (48) in communication with an air intake (52). In a first rotational position the movable member blocks liquid flow out of the unit as well as air flow into the unit. In a second rotational position, the fluid hole on the unit is in communication with the liquid outlet opening of the movable member while the air flow into the unit remains blocked. In a third rotational position, the fluid hole in the wall is fully aligned with the elongated slot on the movable member while the air passage on the movable member is aligned with the vent hole in the unit. This enables air to enter the unit and the liquid to readily escape through the liquid outlet of the movable member.

I claim: 
     
       1. A self venting drain valve for draining liquid contained in a generally air tight container, said container including a wall on a lower portion thereof, comprising: a fluid hole in said wall for passing liquid therethrough, said fluid hole communicating with the interior of said container through a first opening;   a vent hole in said wall for passing air therethrough, said vent hole disposed of said fluid hole and communicating with the interior of said container through a second opening, said first and second openings located generally at the same vertical elevation in said container;   a movable member mounted for movement in a first direction on said container, said member including; a planar face adjacent said wall, said planar face in blocking relation of said fluid hole and vent hole when said member is in a first position;   said member further including fluid accepting means in said face for accepting liquid delivered at said fluid hole, said fluid accepting means in fluid communication with said fluid hole when said member is in a second position and a third position;   a liquid outlet in fluid communication with said fluid accepting means; and   an air passage through said member, said air passage terminating at an air inlet opening in said face, said air inlet opening in communication with said vent hole when said member is in the third position; whereby when said member is in the first position said drain valve is closed, upon movement of said member in the first direction to the second position, said container is placed in a negative pressure condition and upon further movement of said member in said first direction to a third position, air is enabled to enter said container through said air passage enabling liquid to drain through said liquid outlet.       
     
     
       2. The drain valve according to claim 1 and further comprising sealing means for sealing said wall and said movable member in fluid tight relation. 
     
     
       3. The drain valve according to claim 1 wherein said fluid hole is elongated in the first direction whereby said fluid hole is in overlapping relation with the fluid accepting means of said movable member in said second and third positions. 
     
     
       4. The drain valve according to claim 3 wherein said fluid accepting means is an elongated slot in said member, said elongated slot is elongated in said first direction. 
     
     
       5. The drain valve according to claim 4 wherein said slot includes a slot opening, said slot opening and said fluid hole being similar in configuration and aligned when said member is in the third position. 
     
     
       6. The drain valve according to claim 5 wherein said vent hole and said air inlet opening are similar in configuration and fully aligned when said member is in the third position. 
     
     
       7. The drain valve according to claim 6 and further comprising sealing means for sealing said fluid hole and said slot opening and said vent hole and said air inlet opening in fluid tight relation. 
     
     
       8. The drain valve according to claim 7 wherein said sealing means includes an elastomeric sheet, said sheet including a liquid access opening and an air access opening therethrough, said liquid access opening in fluid communication with said fluid hole and configured similarly thereto, and said air access opening being in fluid communication with said vent hole and configured similarly thereto. 
     
     
       9. The drain valve according to claim 7 and further comprising a recess in an outer portion of said planar wall and wherein said sealing means includes an elastomeric gasket positioned in said recess. 
     
     
       10. The drain valve according to claim 8 wherein said sealing means further comprises biasing means for biasing the said movable member against said elastomeric sheet. 
     
     
       11. The drain valve according to claim 10 wherein said movable member is rotatable about a pivot axis and said first direction is a first rotational direction. 
     
     
       12. The drain valve according to claim 11 wherein said movable member is generally cylindrical and the air inlet opening and the slot opening are generally opposed of said pivot axis. 
     
     
       13. The drain valve according to claim 12 and further comprising a pivot post extending from said wall along said pivot axis, said movable member journaled on said pivot post. 
     
     
       14. The drain valve according to claim 13 wherein said pivot post extends through said movable member, and further comprising retaining means at a distal end of said pivot post for holding said member to said container. 
     
     
       15. The drain valve according to claim 14 wherein said biasing means is a spring positioned coaxial with said pivot post and between said retaining means and said movable member. 
     
     
       16. The drain valve according to claim 15 wherein said spring is a wave spring. 
     
     
       17. The drain valve according to claim 16 and further comprising an air intake at the outer surface of the air passage through the member, and wherein the ratio of the area of the liquid outlet and the air intake is generally 2:1. 
     
     
       18. The drain valve according to claim 17 and further comprising first stop means for preventing rotation of said member in the first direction when said member is in the third position. 
     
     
       19. The drain valve according to claim 18 wherein said first stop means comprises a projection extending from said member and a first protuberance extending from said wall, said projection and said first protuberance being in engagement in the third position to prevent further rotation in said first direction. 
     
     
       20. The drain valve according to claim 19 and further comprising second stop means for preventing rotation of said member in a second direction opposed of said first direction when said member is in the first position. 
     
     
       21. The drain valve according to claim 20 wherein said second stop means comprises a second protuberance extending from said wall, said projection and said second protuberance engaging in said first position to prevent further rotation of said member in said second direction. 
     
     
       22. A self venting drain valve for draining liquid contained in a generally air tight container, comprising: a generally planar wall on a lower portion of said container;   a fluid hole extending through said planar wall and communicating with the interior of said container through a first opening, said fluid hole elongated in a first arcuate direction about a pivot axis, said pivot axis generally perpendicular of said planar wall;   a vent hole extending through said planar wall, said vent hole disposed of said fluid hole and communicating with the interior of said container through a second opening, said first and second openings located generally at the same vertical elevation in said container;   a movable member mounted to said vessel, said member being mounted for rotational movement about said pivot axis, said movable member including a planar face in opposed relation of said planar wall, said movable member including a slot in said planar face, said slot arcuately elongated in said first direction and in fluid communication through said member with a fluid outlet, said slot configured similarly to said fluid hole; said member being movable from a first position wherein said planar face is in blocking relation of said fluid hole, through a second position wherein said fluid hole and said slot are in overlapping relation, to a third position wherein said fluid hole and said slot are in alignment, said movable member further including in its planar face an air inlet opening, said air inlet opening in fluid communication through said member with an air intake, said air inlet opening configured similarly to said vent hole, said planar face of said member being in blocking relation of said vent hole in said first and second positions, and said vent hole and said air inlet openings being in alignment with said member is in the third position.